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Id trapezium ABCD (adjoining figure), side AB || side DC, diagonals AC and BD intersect in point O. If AB = 20, DC = 6, OB = 15, then find OD. |
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Answer» side AB || side DC [Given] and seg BD is their transversal. ∴ ∠DBA ≅ ∠BDC [Alternate angles] ∴ ∠OBA ≅ ∠ODC (i) [D – O – B] In ∆OBA and ∆ODC ∠OBA ≅ ∠ODC [From (i)] ∠BOA ≅ ∠DOC [Vertically opposite angles] ∴ ∆OBA ~ ∆ODC [AA test of similarity] ∴ OB/OD = AB/DC = [Corresponding sides of similar triangles] ∴ 15/OD = 20/6 ∴ OD = x = (15 x 6)/20 ∴ OD = 4.5 units |
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